Biofilm Formation and Detection of icaD Gene in Staphylococcus aureus Isolated from Clinical Specimens

Samjhana Karki1, Anil K. Sah2, *, Jayram Lamichhane1, Anjali Maharjan1, Laxmi Sharma2, Rima Rajbhandari3, Shreeya Parajuli3, Samir Acharya3, Santosh Khanal1
1 National College, Khusibu, Kathmandu, Nepal
2 Annapurna Research Center, Maitighar, Kathmandu, Nepal
3 Annapurna Neurological Institutes and Allied Sciences, Kathmandu, Nepal

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© 2019 Karki et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at Annapurna Research Center, Maitighar, Kathmandu, Nepal, E-mail:



S. aureus is found to be a major source of community as well as hospital acquired infections. The increase in antimicrobial resistance and emergence of multidrug resistance has become a big threat worldwide. The biofilm formation of S. aureus influenced the survival and persistence in both environment and host.


The study was conducted with the aim to evaluate in-vitro biofilm formation and the presence of icaD gene in S. aureus from clinical isolates of S. aureus.


A total of 570 wound/pus samples were processed by standard microbiological techniques. Colony morphology, Gram’s staining and biochemical tests were used for the identification of S. aureus. Antimicrobial susceptibility test was performed by Kirby-Bauer disc diffusion technique and methicillin-resistant S. aureus was detected by using cefoxitin antibiotics. The production of biofilm was screened by Congo Red Agar and finally, the presence of icaD gene was determined by PCR.


Out of 570 samples, a total 19.3% (110/570) samples showed the growth of S. aureus. Among which 59.1% (65/110) were multi-drug resistant. Similarly, 26.4% (29/110) isolates were methicillin-resistant S. aureus. Among MRSA isolates 93.1% (27/29) were MDR with more than 3 classes of antibiotics. Biofilm production was shown by 95.45% (105/110) and 77.3% (85/110) isolates on Congo Red Agar and presence of icaD gene respectively.


In this study, the significant association was observed in phenotypic production of biofilm and the presence of icaD gene for the genotypic expression of biofilm. There were also increasing rates of MRSA and multidrug resistance S. aureus.

Keyword: Biofilm, icaD, Methicillin resistant Staphylococcus aureus, Multidrug resistance, Meningitis.